scholarly journals DC Offset Error Compensation Algorithm for PR Current Control of a Single-Phase Grid-Tied Inverter

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2308 ◽  
Author(s):  
Jae Lee ◽  
Seon-Hwan Hwang
Keyword(s):  
Fundamental Frequency ◽  
Error Compensation ◽  
Single Phase ◽  
Detection Method ◽  
Current Control ◽  
Dc Offset ◽  
Phase Current ◽  
Compensation Algorithm ◽  
Dc Component ◽  
Offset Error

In a single-phase grid-tied inverter, the direct current (DC) offset error included in the measured grid side phase current has various causes, such as a non-ideal current sensor, unbalanced power supply of an operational amplifier, and nonlinear features of analog components in interface circuits, etc. If the DC offset error is included in the measured current, it causes the secondary harmonic of fundamental frequency and the DC component in grid phase current which result in degradation of inverter performance. In this paper, a theoretical detection method of the secondary harmonic of the fundamental frequency and a DC component in grid phase current for a proportional-resonant (PR) current control system is introduced. Based on the detection method, an algorithm for compensating DC offset error is also presented for single-phase grid-tied inverters. Simulation results and experimental verification of the DC offset error compensation algorithm are shown in this paper.

scholarly journals A unified method for signal parameter estimation of arbitrarily distorted single-phase grids with DC-offset

2020 ◽  
Author(s):  
Christoph Hackl
Keyword(s):  
Fundamental Frequency ◽  
Single Phase ◽  
Adaptive Observer ◽  
Pole Placement ◽  
Estimation Methods ◽  
Dc Offset ◽  
Low Pass ◽  
Harmonic Components ◽  
Low Pass Filters ◽  
Unified Method

A unified method is presented which allows to<br>estimate all harmonic components, DC-offset and fundamen-<br>tal frequency in arbitrarily distorted single-phase grids us-<br>ing a frequency-adaptive observer (FAO) consisting of modi-<br>fied Second-Order Generalized Integrators (mSOGIs), a DC-<br>Integrator (DCI) and a modified Frequency Locked Loop<br>(mFLL). DCI and mSOGIs are tuned by pole placement which allows for an arbitrarily fast detection of DC-offset and harmonic components if the fundamental frequency is known. If the fundamental frequency must be estimated as well, a mFLL with Gain Normalization (GN), Rate Limitation (RL), Anti-Windup (AW) strategy and low-pass filters (LPF) must be employed. The effectiveness of the proposed FAO is validated by experimental results and its enhanced performance is shown by comparisons<br>to existing estimation methods.

scholarly journals A unified method for signal parameter estimation of arbitrarily distorted single-phase grids with DC-offset

2020 ◽  
Author(s):  
Christoph Hackl ◽  
Markus Landerer
Keyword(s):  
Fundamental Frequency ◽  
Single Phase ◽  
Adaptive Observer ◽  
Pole Placement ◽  
Estimation Methods ◽  
Dc Offset ◽  
Low Pass ◽  
Harmonic Components ◽  
Low Pass Filters ◽  
Unified Method

A unified method is presented which allows to<br>estimate all harmonic components, DC-offset and fundamen-<br>tal frequency in arbitrarily distorted single-phase grids us-<br>ing a frequency-adaptive observer (FAO) consisting of modi-<br>fied Second-Order Generalized Integrators (mSOGIs), a DC-<br>Integrator (DCI) and a modified Frequency Locked Loop<br>(mFLL). DCI and mSOGIs are tuned by pole placement which allows for an arbitrarily fast detection of DC-offset and harmonic components if the fundamental frequency is known. If the fundamental frequency must be estimated as well, a mFLL with Gain Normalization (GN), Rate Limitation (RL), Anti-Windup (AW) strategy and low-pass filters (LPF) must be employed. The effectiveness of the proposed FAO is validated by experimental results and its enhanced performance is shown by comparisons<br>to existing estimation methods.

scholarly journals Control Comparison for the Coordinate Transformation of an Asymmetric Dual Three Phase Synchronous Motor in Healthy and Single-Phase Open Fault States

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1735
Author(s):  
Dong-Kyun Son ◽  
Soon-Ho Kwon ◽  
Dong-Ok Kim ◽  
Hee-Sue Song ◽  
Geun-Ho Lee
Keyword(s):  
Coordinate Transformation ◽  
Single Phase ◽  
Transformation Method ◽  
Synchronous Motor ◽  
Current Control ◽  
Control Logic ◽  
Phase Current ◽  
Healthy State ◽  
Three Phase ◽  
Fault State

The coordinate transformation method of asymmetric dual three phase synchronous motor (ADTP-SM) is a Double dq transform using two dq-axes and a vector space decomposition (VSD) model method using the orthogonality of ADTP-SM. There are several studies comparing the two methods in a healthy state, but few in a single-phase open fault state. In the healthy, when the VSD model is applied, different harmonic orders of the phase current are projected onto the dq and xy-axes (the axis for controlling harmonics of the phase current), and the two-axes are orthogonal, so it can be controlled stably. In the single-phase open fault state, the same current control logic as in the healthy situation is applied. When applying the Double dq transform, the dq-axis of the fault set fluctuates, and it affects the healthy set, so it cannot be controlled stably. When applying the VSD model, if both the dq-axis and the xy-axis are controlled, the two coordinate systems do not have orthogonality and cannot be stably controlled, due to mutual interference. However, if only the dq-axis is controlled, it can be controlled stably because there is no Cartesian coordinate system other than the dq-axis. In the healthy state and single-phase open fault state, the equation is verified through experiments and simulations, and the control stability according to the coordinate transformation is compared.

scholarly journals A Stationary Reference Frame Current Control Algorithm for Improvement of Transient Dynamics of a Single Phase Grid Connected Inverter

Electronics ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 722 ◽  
Author(s):  
Horyeong Jeong ◽  
Jae Suk Lee
Keyword(s):  
Reference Frame ◽  
Disturbance Rejection ◽  
Control Algorithm ◽  
Single Phase ◽  
Current Control ◽  
Phase Lag ◽  
Phase Current ◽  
Disturbance Rejection Control ◽  
Stationary Reference Frame ◽  
Grid Connected Inverter

This paper proposes a stationary reference frame current control algorithm for a single-phase grid-connected inverter (GCI) for improvement of transient dynamic performance. Disturbance, i.e., grid voltage in a target system, is estimated using a stator current observer, and the estimated disturbance is applied to a current controller for implementation of disturbance rejection control (DRC). In the proposed current control algorithm, the disturbance rejection control algorithm is applied to reduce the overcurrent occurring in the single-phase grid-connected inverter when grid faults happen. In this paper, the AC phase current of a single-phase inverter is controlled, instead of the current vector, which is a DC signal. To compensate for the drawbacks of controlling the AC phase current, such as phase lag and steady-state error, command feedforward control is also applied in the proposed control system. The proposed control algorithm is mathematically derived and represented in transfer functions and implemented via simulation and experiment.

scholarly journals Output Voltage Imbalance Compensation Using dc Offset Voltage for Split dc-Link Capacitor 3-Leg Inverter

Electronics ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1029
Author(s):  
Sun-Pil Kim ◽  
Sung-Geun Song ◽  
Sung-Jun Park ◽  
Feel-soon Kang
Keyword(s):  
Output Voltage ◽  
Harmonic Distortion ◽  
Neutral Point ◽  
Total Harmonic Distortion ◽  
Phase 3 ◽  
Dc Offset ◽  
Phase Current ◽  
Compensation Algorithm ◽  
Offset Voltage ◽  
Circuit Structure

In this paper, we analyzed the output voltage imbalance and the cause of the offset voltage in 3-phase 3-leg inverters by using Millman’s theory. Based on this result, we proposed a voltage imbalance compensation algorithm using the dc offset voltage that appeared at the neutral point voltage of the load. To apply the proposed imbalance compensation algorithm, it needs a circuit structure of 3-phase 4-wire such as split dc-link capacitor 3-leg inverter and 4-leg inverter. Therefore, the total harmonic distortion (THD) of the load phase current according to the imbalance rate of the load was analyzed for the two inverters. Then, PSIM simulation and experiments based on a 10 kW-prototype of split dc-link capacitor 3-leg inverter were implemented to verify the validity of the proposed imbalance compensation algorithm.

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